Fungal community composition and function in different spring rapeseeds on the Qinghai-Tibet Plateau, China

Fungi play a crucial role in the development of rapeseed and influencing the functioning of agroecosystems. However, the fungal composition and function in spring rapeseed on the Qinghai-Tibet Plateau (QTP) remain unclear.

The agronomic traits, rhizosphere soil properties, and fungal communities across multiple niches within seven cultivars of Brassica rapa L. and Brassica napus L. were investigated using cultivation, physiological assay, and high-throughput sequencing.

We found significant differences in growth indices, yields and fungal diversity among leaf, stem, and root compartments of B. napus, especially in late-maturing cultivars, compared to B. rapa. Interestingly, defense-related indices and fungal diversity in rhizosphere soil exhibited the opposite trend. A total of 12 phyla, 55 orders and 200 genera were identified. The predominant genera were Olpidium (66.29%), Lactarius (18.37%), Verticillium (1.99%), Mortierella (0.78%) and Cystofilobasidium (0.56%). The rhizosphere soil had a higher abundance of Olpidium and Mortierella than other ecological niches, while the stem harbored more Lactarius and Verticillium. In addition, 46 key genera were widespread across all niches and cultivars, and 19 biomarkers were significantly enriched, with saprotroph-symbiotroph, symbiotrophs and pathotroph-symbiotroph trophic groups dominating. Alternaria isolated from rapeseed, which was also identified as one of the most abundant, key and biomarker genera, effectively facilitated the germination of B. rapa under chilling and drought stress.

The joint influence of numerous important fungal genera can promote the growth and yield of rapeseed. Our results provide valuable insights into the complex relationship between rapeseed and fungal communities on the QTP.